I have a 4th gen 20gb iPod - it has been working fine - however now when I try to charge it via my USB port I get the very flat battery icon (which they say should take 30 min before it has enough power to mount)Every 15 mins or so the iPod mounts into iTunes - but only stays there for about 30 seconds before the "Not enough battery Power" message comes iup - just a viscious circle - I've been trying it all day ... nay suggestions (i don't have a wall or dock charger)